This research proposal aims to develop the phenomenon of cytoplasmic incompatibility as a general tool for the genetic manipulation of insect disease vectors, in order to reduce their vector competence for certain human pathogens. It primarily focuses on utilizing the reproductive advantage accrued to insects that carry the intracellular bacterial symbiont, Wolbachia pipientis, as a means to drive desirable genes into natural insect vector populations. It also aims to develop the necessary technology needed to utilize Wolbachia pipientis as a gene expression vector within insect tissue. One of the ultimate aims of this project is the introduction and expression of gene constructs in Wolbachia as a means to target disease agents directly within insect cells. 1. The extent of natural Wolbachia infection will be determined in representative mosquito species using the recently developed diagnostic PCR assay. 2. Wolbachia will be transferred into the uninfected mosquito disease vectors, Aedes aegypti, Aedes triseriatus and Anopheles gambiae using embryonic microinjection techniques. 3. These trans-infected mosquito species will be tested for their ability to express the cytoplasmic incompatibility phenotype using conventional genetic crossing techniques. 4. The technology will be developed to transform Wolbachia with broad host range plasmids in order to use this bacterium as an expression vector in insect tissue.